Wire Bump Material

ABSTRACT

The present invention was held in order to resolve problems on above-mentioned conventional wire bumping material. This invention has the following purposes; (1) approximating Au—Ag alloy bumping balls to bond Al pads to ideal sphere shape (2) increasing assurance of Au—Ag alloy bump bonding to Al pads (3) shortening tail length of Au—Ag alloy bump (4) improving anti-Au consumption into solder (5) decreasing contamination of capillary tip by bump wire and hole around tip Means for resolution Au—Ag alloy for wire bumping comprising wherein Au, which purity is more than 99.99 mass %, comprising Au matrix and a particle of additive elements, consisting of 1 to 40 mass % Ag, which purity is more than 99.99 mass %.

This application is based on Japanese Patent Application No.2004-287599, filed on Nov. 30, 2004, the entire contents of which areincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to metal alloy or material for wirebumping to form bump, using wire bonding technique.

STATE OF THE ART

Conventionally, it is known that method of forming metallic bump, usingwire bonding method, bonding with electrodes on the IC chips ortransistors and leads of TAB (Tape Automated Bonding), lead framesand/or outer terminals on ceramic substrates. This wire bumping methodhas an advantage to manufacture high density packages and thin typepackages, because of direct bonding to electrode pads on IC chips andouter terminals through bump and lower height of bonded part comparingwith a case of using wire-bonding. For example, there are flip chipmethod, forming bumps on electrodes of IC chip in advance, bonding withthese bumps against molten solder on conductive circuit of printedcircuit substrate, and also film carrier method, molten bonding with Cutape plated solder.

High purity Au, under constraint of which purity should be more than99.99 mass %, has been used for wire bumping alloy so far. Whereas inthe case of using high purity Au, after ultrasonic bonding to IC chipforming balls on ultra fine wire in advance, tearing off a part of thewire held with a clamp, problem occur that tails, which is principalcause of incorrect contact, remained on the side of bumps, namely onremained balls of IC chips. Hence study on shortening the length oftails had been done such as Au matrix alloy consisting of 0.5 to 10weight % Pd (Japanese Patent No. 2737953) and Au matrix alloy consistingof 0.003 to 5 weight % Pd(Japanese Patent Application Laid-OpenPublication No. 9-321076), and Au matrix alloy consisting of 0.001 to 5weight % Pt, Pd and/or Ru (Japanese Patent Application Laid-OpenPublication No. 10-287936). However, genus of platinum, like Pd, etc. isvery expensive, moreover it is necessary specific facilities and moreexpensive comparing with Au, conventionally had been used as purity of99.9% Au, which contained much impurities. Moreover, increasingadditives of genus of platinum, inside of capillary is contaminated, andthis contamination make non-spherical ball attached to wire, and ballsbecome harder and Si chip is broken under Al pad, for such problems,practically, it had been used Au-1% Pd alloy.

Though this Au-1% Pd alloy has advantage such as effect of repression ofAu—Al compound growth between Al pad and Au—Pd alloy bump, at the momentof tearing off, still long tails emerge occasionally. Moreover, recentlysoldering process tend to operate at higher temperature such as 200° C.to 300° C., especially in the case of Pb-free Sn matrix soldering,higher temperature operation is noticeable. When operating temperaturebecome higher temperature, phenomena of solder consumption occur, namelyAu rapidly melt into solder, it is forced to operate soldering understrict temperature control. Though Au-5% Pd alloy has been studied, ballbonding in the air, because of forming hard balls, problem of graterchip damage against Al pad, and problem of big fluctuation of Pd marketprice, said capillary contamination and length of tails, it had not beenin practical use.

DISCLOSURE OF INVENTION Issues to be Solved by the Present Invention

The present invention has been done to solve above-mentioned problems ofconventional Au alloy for wire bumping.

The present invention has the following purposes;

(1) approximating Au—Ag alloy bumping balls to bond Al pads to idealsphere shape

(2) increasing assurance of Au—Ag alloy bump bonding to Al pads

(3) shortening tail length of Au—Ag alloy bump

(4) improving anti-Au consumption into solder

(5) decreasing contamination of capillary tip by bump wire and holearound tip

According to the present invention, there are provided following wirebumping materials;

(1) Au—Ag alloy for wire bumping comprising featured wherein Au, whichpurity is more than 99.99 mass %, comprising Au matrix and 1 to 40 mass% of Ag, which purity is more than 99.99 mass %.

(2) Au—Ag alloy for wire bumping according to above-mentioned (1),featured wherein said a particle of additive elements, consisting of 5to 50 mass ppm of Ca, 1 to 20 mass ppm of Be and/or 5 to 90 mass ppm ofrare-earth elements.

(3) Au—Ag alloy for wire bumping according to above-mentioned (1),featured wherein said a particle of additive elements, consisting of 10to 90 mass ppm of one element, at least, selected from a groupconsisting of Ge, Mg, Sr, Bi, Zn, Si, Ga, Sn, Sb, Li, and alloy thereof.

(4) Au—Ag alloy for wire bumping according to above-mentioned (1),featured wherein said a particle of additive elements, consisting of 5to 50 mass ppm of Ca, 1 to 20 mass ppm of Be and/or 10 to 90 mass ppm ofat least one element among rare-earth elements selected from a groupconsisting of Ge, Mg, Sr, Bi, Zn, Si and Ga, wherein said in the case ofsingle element; B or Li, 0.5 to 40 mass ppm.

(5) Au—Ag alloy for wire bumping according to above-mentioned (1), (2),(3) and (4), featured wherein said Au matrix consisting of 5 to 25 mass% of Ag.

(6) Au—Ag alloy for wire bumping according to above-mentioned (2) or(4), featured wherein said a particle of additive rare-earth elements,consisting of Y, La, Ce, Eu, Nd, Gd, Sm, and alloy there of.

(7) Au—Ag alloy for wire bumping according to above-mentioned (1) to(6), featured wherein said bonding to Pb matrix solder or Sn matrixsolder.

(8) Au—Ag alloy for wire bumping according to above-mentioned (1) to(6), featured wherein said flip chip bonding to Pb-free Sn matrixsolder.

(9) Au—Ag alloy for wire bumping according to above-mentioned (1) to(6), featured wherein said flip chip bonding to Pb-free Sn matrixsolder, which has 170° C. to 260° C. melting point.

EFFECTS OF THE PRESENT INVENTION

Effect of approximating Au—Ag alloy soft bumping ball shape to bond Alpads to ideal sphere shape is accounted hereinafter.

Using Au—Ag alloy of the present invention, because a spherical softball is formed during ball forming process in the air, Al pad on chiphas no damage. Moreover, Ca. Be or rare-earth elements, or a particle ofgroup of elements such as Ge, Mg, Sr, Bi, Zn, Si, Ga, Sn, Sb, B or Liare oxidized during bonding to Al pad, abnormal shape of balls is notgenerated. Consequently it is absolutely able to ball-bond for bump-wirewith set circular area at appropriate position even in the case ofsmaller pad area.

Next effect of increasing assurance of Au—Ag alloy bump bonding to Alpad is accounted hereinafter. In the case of high purity Au—Ag alloymatrix of the present invention, since at pure Al or Al alloy padsformation of inter-metallic compounds between Al and Au will be delayed,Au₄Al does not generate among these inter-metallic compounds, soassurance of bonding to Al pads increase. It is available that Al padsare pure Al or Al principal content alloy, for instance, 80% Al—Cu alloyetc. Moreover, in the case of plastic mold, because inter-metalliccompounds do not generate, it is able to prevent corrosion attacked byhalogen from contained plastic.

Next effect of shortening tail length of Au—Ag alloy bump is accountedhereinafter.

In the case of high purity Au—Ag alloy matrix of the present invention,a particle of additive elements works effectively than that of pure Aumatrix, even if in the case of maximum content of a particle of additiveelements and impurity elements only 100 ppm (where exception Ag),dispersion of bump tails are smaller. Since the smaller dispersion ofbump tails, the more homogenous bumps is able to be manufactured, thereare greater deference of neck strength, and effect of stability for manynumber of bumps.

Next effect of improving anti-Au consumption into solder is accountedhereinafter.

In the case of high purity Au—Ag alloy matrix of the present invention,because of improving anti-Au consumption into solder, Au—Ag alloy bumpdoes not disappear into solder during flip chip bonding. For thisreason, range of selection of solder is expanded, through hightemperature reflow after soldering, flip chip bond, which has stablebonding strength is attained. Since range of temperature is broader forusable specific solder, work management of soldering is loosened.Moreover, as it is able to manufacture homogenous bumps as small asdispersion of bump tails, it is able to disappear selectively only partof tails of Au—Ag alloy bump, therefore distribution of tail lengthbecome more and more small. Especially in the case of 5 to 25 mass % ofAg in the Au—Ag alloy matrix, as improving anti-Au consumption intosolder at high temperature, stable flip chip structure is obtained.Moreover since decreasing consumption such as elements of Au etc. intosolder, fragile compounds do not grow in solder.

DESCRIPTION OF THE MOST PREFERRED EMBODIMENT

Wire bump material of the present invention is Au—Ag alloy and a partialof additive elements. Content of Ag is 1 to 40 mass %, preferably, 5 to25 mass %. Purity of Ag is more than 99.99 mass %.

In the first preferred embodiment of the present invention, Ca, Beand/or rare-earth elements (so called as Group A elements) are used.These elements are available to select single or combination of morethan 2 elements. Content of these elements, in the case of Ca, is 5 to50 mass ppm, and more preferable 8 to 35 mass ppm. In the case of Be, itis 1 to 20 mass ppm, more preferable 3 to 18 mass ppm. In the case ofrare-earth elements, it is 5 to 90 mass ppm. In the case of plural useof these elements, the total amount of content should be less than 90mass ppm, more preferable less than 50 mass ppm. As rare-earth elementsare selected from Y, La, Ce, Eu, Nd, Gd and Sm, at least one elementshould be selected preferably.

In other preferred embodiment of the present invention, a particle ofadditive elements are selected from Ge, Mg, Sr, Bi, Zn, Si, Ga, Sn, Sb,B and Li, at least one element should be selected preferably. Content ofthese elements (so called as Group B elements) is 10 to 90 mass ppm.Especially preferable elements are Ge, Bi, Si, Sn, Sb, B and/or Li.

In the case of using Ge, Bi, Si, Sn and/or Sb (so called as Group B¹),content is 10 to 90 mass ppm, more preferable 15 to 60 mass ppm.

In other preferred embodiment of the present invention, combination ofelements of Group A and Group B is used. In this case, content of GroupA, in the case of said Ca, content is 5 to 50 mass ppm, more preferable8 to 35 mass ppm, in the case of Be, content is 1 to 20 mass ppm, morepreferable 3 to 18 mass ppm, in the case of rare-earth elements, contentis 3 to 90 mass ppm. In the case of plural elements of Group A, thetotal amount of content should be less than 90 mass ppm, more preferableless than 50 mass ppm.

In the case of using Group B, said elements are only B and/or Li (socalled as Group B²), content is 0.5 to 40 mass ppm, more preferable 0.5to 15 mass ppm. In the case of plural elements of Group B², the totalamount of content should be less than 15 mass ppm preferably. In thecase of consisting of Group A, Group B¹ and Group B², the content ofsaid Group B² is 0.5 to 40 mass ppm, more preferable 0.5 to 15 mass ppm.Moreover, in this case, the total amount of content should be less than90 mass ppm, preferably less than 50 mass ppm. Effect of approximatingAu—Ag alloy bumping balls to bond Al pads to ideal sphere shape isaccounted hereinafter.

In general, it is easy to obtain ideal spherical balls in the case of Aualloy, which purity is higher 99.99 mass % with a partial of additiveelements, also in the case of Au-several % Pd alloy in the air. In thecase of Au—Ag alloy, Ag is apt to capture oxygen from high temperatureair, increasing content of Ag, a partial of additive elements isoxidized and is apt to form abnormal shape of balls, then during bondingit cause of damage into Al pads. Hence the upper limit of content of Agshould be less than 40 mass %, so circular bonds are obtained on the Alpads through ball-bonding in the air. Moreover, using purity of 99.99mass % of Ag, though concentrated Ag into Au, soft balls are obtainable,and adding a partial additives in order to obtain true sphere, such asCa is 5 to 50 mass ppm, Be is 1 to 20 mass ppm and/or rare-earthelements are 5 to 90 mass ppm, or at least one element from Ge, Mg, Sr,Bi, Zn, Si, Ga, Sn, Sb, B or Li, the total amount of content is 10 to 90mass ppm (where in the case of single use of B and Li, 10 to 90 massppm).

Former said a partial of additive elements (Group A) has grater rollagainst Au—Ag matrix than that of latter Group B elements. Hereinafter,the reason of set 5 to 50 mass ppm of Ca among the former said a partialadditive elements it become to be difficult to approximate shape ofballs to true sphere under condition of less than 5 mass ppm, on thecontrary, shape of balls is apt to deform under condition of excess 50mass ppm. The upper limit and lower limit for Be and rare-earth elementsare from same reason. Especially Y, La, Ce, Eu and Nd among rare-earthelements at the range of content from 10 to 90 mass ppm are apt toobtain circular bumps. On the other hand, the latter Group of elementsconsist of eutectic alloy with Au has more feeble effect to form spheresin the air than that of former elements to Au—Ag matrix, when the totalamount of content is 10 to 90 mass ppm selected at least one element,from Ge, Mg, Sr, Bi, Zn, Si, Ga, Sn, Sb, B and Li (where in the case ofsingle use of B and Li, 0.5 to 40 mass ppm), Au—Ag alloy bumps areformed with no problem in practical use corresponding to small pitch,moreover to meet to purity of 99.99 mass % of Au alloy (where exceptcontent of Ag) Less than 10 mass ppm of these elements (in the case ofsingle use of B and Li, 0.5 mass ppm), it is not able to obtainpreferable true circular shape.

Moreover, exceed 90 mass ppm does not meet to purity 99.99 mass % Au(where without Ag). so inconvenience of display as “High purity Au” willoccur and in the case of heterogeneous alloy, the Au—Ag alloy becomes tobe difficult to form and approximate the balls to sphere shape on Alpads. Especially in the case of single use of B and Li, exceed of 40mass ppm is apt to difficult to form ball to sphere shape.

Purity of 99.99 mass % of Au alloy contains these former and lattergroup of a partial of additive elements and inevitable impurity elements(where except Ag), which is less than 100 mass ppm in maximum, so it isalways able to form stable circular shape.

Effect of increasing assurance of Au—Ag alloy bump bonding to Al pads isaccounted hereinafter.

It is known that for Au—Ag alloy matrix comparing with Pure Au matrixand Au—Pd alloy matrix, there is delay to generate inter-metalliccompound between Al and Au at Al pad, and there is no Au₄Al in thisinter-metallic compound. It is also found that Au₄Al in Pure Au matrixand Au—Pd alloy matrix is not generated, a partial of additive elementsof the present invention for bump in Au—Ag alloy matrix remain in matrixand has no reaction with Al. Thus Au—Ag alloy matrix has a roll to delayof generating inter-metallic compounds comparing with Pure Au matrix andAu—Pd alloy matrix. Moreover, in the case of Au—Ag alloy matrix added apartial of additive elements above-mentioned, ideal sphere shape isobtained. Besides, in the case of a partial of additive elementscontains only less than 100 mass ppm in maximum, as purity 99.99 mass %of Au—Ag alloy matrix (where without Ag) is maintain, so it is able toincrease assurance of Au—Ag alloy bump bonding to Al pads. Incidentallyit is found that there is no chip damage to Al pad and a partial ofadditive elements disperse finely by conventional dissolution andcasting process, if total content is 0.009 to 0.3 mass ppm at least morethan one element of Ge, Mg, Sr, Bi, Zn, Si, Ga, Sn, Sb and Li.

Effect of shortening tail length of Au—Ag alloy bump is accountedhereinafter.

Inventors of the present invention considered that dispersion of taillength of bump is difference between strength of bump wire itself andstrength of heat affected part (so called “neck strength difference”).In the case of less than 1 mass % Ag in the Au—Ag alloy matrix, Au—Agalloy matrix itself becomes rather soft, yet adding a set of a partialof additive elements as same as Pure Au matrix. In the case of bump wirebecoming soft, strength of wire become weak and neck strength differencebecome small. Consequently, torn position of bump wire is dispersing,and tail length is apt to disperse. Then using a set of ratio of Au—Agalloy matrix, neck strength difference is able to be grater than that ofPure Au matrix and Au—Pd alloy matrix. Moreover if not adding a set of apartial of additive elements into Au—Ag alloy matrix, heat affected partbecomes broader, because Au—Ag alloy is composed with high pure Au andhigh pure Ag. Consequently, as tail length is apt to have biggerdispersion, a partial of additive elements should be added into Au—Agalloy matrix inevitably. From aspect of neck strength difference,preferable content of Ag in the Au—Ag alloy matrix is the range of 5 to25 mass %. At least adding one element from the group of 5 to 50 massppm of Ca, 1 to 20 mass ppm of Be, or 5 to 90 mass ppm of rare-earthelements, though it is a partial of content, narrowing effect of heataffected zone is grater than that of pure Au matrix and Au—Pd alloymatrix. Especially Y, La, Ce, Eu and Nd among rare-earth elements havegreater effect of narrowing heat affected area. However, if content ofthese elements is less than lower limit, though content of Ag is in therange of 5 to 25 mass % in Au—Ag alloy matrix, as heat affected partbecomes broader, a set of lower limit value is necessary.

By the way, if these elements exceed upper limit, there is narrowingeffect of heat affected area, as above-mentioned, from reasons of shapeof ball become distorted, upper limit is set. On the other side, groupof elements such as Ge, Mg, Sr, Bi, Zn, Si, Ga, Sn, Sb, B or Li haseffect of narrowing heat affected area under condition of comparativelymuch adding.

Moreover, adding exceed of 90 ppm till 0.3 mass %, effect of heataffected part is obtainable, but it does not meet to purity of 99.99mass % of Au alloy (where except Ag), if content exceed of 90 ppm. Theseadditives of former and latter include only below 100 ppm in maximum inpurity of 99.99 mass % of Au alloy (where except Ag), stable effectwhich shortening heat affected area is always obtained. It is found thatif content of Ag is in the range of 5 to 25 mass % in Au—Ag alloymatrix, satisfactory effect of narrowing heat affected part is obtainedin the best way.

Effect of improving anti-Au consumption into solder is accountedhereinafter.

It is known as solder alloy such as principal content of Pb alloy (Pballoy, Pb-0.3 mass % Sn alloy, Pb-5 mass % Sn alloy, etc.), Pb-freealloy (Sn alloy, Sn-3.5 mass % Ag alloy, Sn-0.8 mass % Cu alloy, Sn-0.5mass % Ni alloy, Sn-1.0 mass % Zn alloy, Sn-3.5 mass Ag alloy, 0.5 mass% Cu alloy, Sn-20 mass % In alloy, etc.).

It is found that Au—Ag alloy matrix has better effect to improve anti-Auconsumption into these solder comparing with pure Au matrix, especiallyunder higher temperature condition. Especially, if content of Ag is inthe range of 5 to 25 mass % in Au—Ag alloy matrix under high temperaturecondition, it improves anti-Au consumption into solder. As additiveelements is a partial of content merely affect to anti-Au consumptioninto solder in Au—Ag alloy matrix, Au—Ag alloy matrix with a set of apartial of additive elements improves anti-Au consumption into soldercomparing with pure Au matrix and Au—Pd alloy matrix.

Embodiment OF THE PRESENT INVENTION

Adding a partial of additives elements (where unit is mass ppm) as sameas amount value in the table attached with purity of 99.999 mass % of Auand purity of 99.999 mass % of Ag (where unit is mass %) said embodimentwas dissolved in the vacuum furnace and was cast. Drawing this, at 25 μmdiameter final heat treatment was processed. After using this ultra finewire on 100 μm square Al pad in the air by the Sinkawa wire-bonder(UTC400 type) under condition of 0.5 msec of discharge time balls wereformed, in general condition (ball diameter is 62 μm, deformed diameterof ball is 80 μm) ball bonding was performed, all balls were formedwithin 100 μm square Al pads. The result is shown in the table.

Where “Formability of balls” means that appearance of ball was evaluatedby stereo microscope at magnification of 400× to formed 100 balls, goodappearance is shown as “A”, small cavity but usable is shown as “B”,deformed ball with cavity unusable is shown as “C”. Moreover “Ultrasonicbonding ball diameter” is the mean of ball size on Al pad for each 100balls direction of vertical(Y) and direction of horizontal(X) by Olympaslength measurement microscope. Then the difference from mean wasintroduced by minimum mean square method (shown as “Ultrasonic bondingball stability X/Y”) more than 0.96 value is shown as “A”, 0.90 to lessthan 0.96 value is shown as “B”, less than 0.90 is shown as “C”.Moreover, “Shear strength” is mean of tensile strength when tensileupward (Z direction) for each 100 wires by the Dage Holdings ShearStrength Tester (PC-2400). Where tail length of bump was measured as“Dispersion of neck height (range)”, it is shown as mean. Then smallerthan 20 μm of dispersion of neck height (range) is shown as “A”, 20 μmto less than 30 μm is shown as “B”, bigger than 30 μm is shown as “C”.Moreover “Chip damage” is shown as number of cracks around ball on Alpad observing by 400× stereo microscope, no crack is shown as “A”, 1 to4 cracks is shown as “B”, more than 5 cracks is shown as “C”. Moreover,“Heat test” was held to 100 Au alloy bumps against Sn-3.5% Ag alloy, tokeep flip-chip structure, was reflowed heated at 250° C. for 60 seconds.Then for each 10 section areas were observed by 400× stereoscope, morethan 50% of before reflow section area is shown as “A”, 30% to less than50% is shown as “B”, 10% to less than 30% is shown as “C”, less than 10%is shown as “D”.

At this point, it was found that all of “A”, which has more than 50% ofbefore reflow section area, homogeneously has bump height in solderbecause tail like whisker at tear off moment melted into Sn-3.5% Agalloy. On the other hand, “C”, which has less than 10% of before reflowsection area, bump itself melted into Sn-3.5% Ag alloy and disappear,hence bump bonding was not done. TABLE 1 Ca Be Rare earth element (ppm)Others (ppm) Au Ag % ppm ppm Y La Ce Nd Sm Eu Gd Ge Mg Sr Bi Zn Si Ga SnSb B Li Comparative1 Bal. 0.3 20 Comparative2 Bal. 45 10 10 Comparative3Bal. 15 Comparative4 Bal. 3 20 Comparative5 Bal. 30 10 Comparative6 Bal.10 5 Comparative7 Bal. 15 60 Comparative8 Bal. 20 0.3 Comparative9 Bal.10 30 Comparative10 Bal. 15 2 Comparative11 Bal. 20 20 20 20 20 20Example1 Bal. 10 20 Example2 Bal. 15 10 Example3 Bal. 20 20 Example4Bal. 10 20 Example5 Bal. 15 20 Example6 Bal. 20 20 Example7 Bal. 10 20Example8 Bal. 15 20 Example9 Bal. 20 20 Example10 Bal. 10 50 Example11Bal. 15 20 Example12 Bal. 20 50 Example13 Bal. 10 50 Example14 Bal. 1550 Example15 Bal. 20 50 Example16 Bal. 10 50 Example17 Bal. 15 50Example18 Bal. 20 50 Example19 Bal. 10 1 Example20 Bal. 15 10 Example31Bal. 15 20 10 Example32 Bal. 20 20 10 10 Example33 Bal. 10 10 10 10Example34 Bal. 15 10 10 10 Example35 Bal. 20 10 10 1 10 Example39 Bal.20 10 10 10 10 Example40 Bal. 5 20 20 20 Example41 Bal. 15 50 10 10 10Example42 Bal. 20 10 10 10 Example43 Bal. 5 10 15 30 10 Example44 Bal.15 10 30 10 Example45 Bal. 20 10 50 20 Example46 Bal. 5 10 15 10 10Example47 Bal. 15 5 50 10 Example48 Bal. 20 10 10 20 10 Example49 Bal. 510 15 10 10 Example50 Bal. 15 10 5 50 10 Example51 Bal. 20 10 10 10 1010 20 10 Example52 Bal. 5 10 15 10 10 10 10 10 Example53 Bal. 15 10 5 1050 Example54 Bal. 15 30 5 Example55 Bal. 5 10 15 10 Example56 Bal. 15 530 10

TABLE 2 Pressbonding Pressbonding Dispersion of Heat test ball dia. ballstab. Shear Chip damage neck height Bump Formability X Y X/Y Resultstrength Cluck no. Result Result area Result of balls μm — — kg/mm2 — —μm — % — Comparative1 A 73.0 75.0 0.973 B 9.1 0 A 55 D 1 D Comparative2D — — — — — 28  D — — — — Comparative3 A 68.0 71.2 0.955 D 10.5 0 A 36 D70 A Comparative4 A 72.5 74.4 0.974 B 9.2 0 A 51 D 16 C Comparative5 A65.3 66.6 0.980 B 11.7 2 38 D 85 A Comparative6 A 68.7 69.2 0.993 A 10.20 A 42 D 60 A Comparative7 D — — — — — — — — — — — Comparative8 A 67.271.2 0.944 D 11.0 0 A 40 D 72 A Comparative9 D — — — — — — — — — — —Comparative10 A 68.1 71.7 0.950 10.3 0 A 39 D 64 A Comparative11 D — — —— — — — — — — — Example1 A 68.2 70.1 0.973 B 11.2 0 A 20 A 71 A Example2A 68.5 70.5 0.972 B 11.5 0 A 29 B 76 A Example3 A 67.5 69.3 0.974 B 11.90 A 18 A 83 A Example4 A 67.0 69.7 0.961 B 11.2 0 A 19 A 70 A Example5 A67.4 70.3 0.959 D 11.4 0 A 19 A 77 A Example6 A 67.2 69.5 0.967 B 11.9 0A 17 A 81 A Example7 A 68.5 70.0 0.979 B 11.1 0 A 19 A 70 A Example8 A68.7 70.5 0.974 B 11.4 0 A 20 A 75 A Example9 A 67.6 69.4 0.974 B 11.9 0A 16 A 80 A Example10 A 68.5 69.3 0.988 B 11.1 0 A 18 A 70 A Example11 A67.6 69.1 0.978 B 11.4 0 A 20 A 74 A Example12 A 67.3 68.5 0.982 B 11.80 A 18 A 82 A Example13 A 68.5 69.3 0.988 B 11.2 0 A 20 A 68 A Example14A 67.7 68.7 0.985 B 11.4 0 A 19 A 74 A Example15 A 67.2 68.6 0.980 B11.9 0 A 18 A 82 A Example16 A 68.5 69.8 0.981 B 11.3 0 A 18 A 69 AEvaluation Example17 A 67.8 68.5 0.990 B 11.5 0 A 17 A 73 A Example18 A67.4 68.3 0.987 B 11.9 0 A 18 A 81 A Example19 A 68.4 69.5 0.984 B 11.20 A 22 B 62 A Example20 A 67.6 68.5 0.987 B 11.4 0 A 19 A 77 A Example31A 67.4 68.8 0.980 B 11.6 0 A 16 A 76 A Example32 A 67.4 68.4 0.985 B11.9 0 A 17 A 82 A Example33 A 68.2 69.2 0.986 B 10.2 0 A 18 A 81 AExample34 A 67.5 68.1 0.991 A 10.3 0 A 17 A 77 A Example35 A 67.4 68.30.987 B 11.8 0 A 19 A 80 A Example39 A 67.5 68.3 0.988 B 11.5 0 A 19 A67 A Example40 A 68.2 69.7 0.978 B 9.5 0 A 20 A 26 C Example41 B 67.968.9 0.986 B 10.3 0 A 20 A 75 A Example42 A 67.8 68.3 0.993 A 11.7 0 A19 A 79 A Example43 B 68.7 70.1 0.980 B 9.3 0 A 19 A 28 C Example44 A68.3 69.7 0.980 B 10.1 0 A 20 A 74 A Example45 A 67.6 68.2 0.991 A 11.30 A 18 A 81 A Example46 A 68.5 68.2 0.995 A 9.5 0 A 23 B 33 B Example47A 68.1 69.3 0.982 B 10.3 0 A 20 A 76 A Example48 A 67.8 68.5 0.986 B11.2 0 A 18 A 81 A Example49 A 68.7 69.3 0.991 A 9.5 0 A 20 A 27 CExample50 A 68.3 69.3 0.985 B 10.2 0 A 19 A 74 A Example51 A 68.4 69.20.988 B 11.2 0 A 20 A 80 A Example52 A 68.8 69.4 0.991 A 9.3 0 A 24 B 34B Example53 A 68.2 69.2 0.986 B 10.1 0 A 19 A 77 A Example58 A 69.5 70.90.980 B 10.1 0 A 19 B 77 A Example59 A 68.8 70.6 0.975 B 9.6 0 A 21 A 32B Example60 A 68.8 70.2 0.981 B 10.5 0 A 20 A 74 A Evaluation A Good — ——   0.96≦ — — 0 — <20 — 50%< B Small cavity — — — <0.96 — — <5  — <30 —30%< C — — — — — — — — — — — 10%< D Unusable — — — <0.90 — —  5≦ — ≦30 — ≦10%  

1. Au—Ag alloy bump comprising: 1-25 mass % of Ag of purity of 99.99mass % or higher; at least one of 5-50 mass ppm of Ca, 1-20 mass ppm ofBe, and 5-90 mass ppm of rare earth element; and the balance Au ofpurity of 99.99 mass % or higher.
 2. (canceled)
 3. Au—Ag alloy bumpaccording to claim 1, further comprising 10 to 90 mass ppm of at leastone element selected from a group consisting of Ge, Mg, Sr, Bi, Zn, Si,Ga, Sn, Sb, B and Li.
 4. Au—Ag alloy bump according to claim 1, furthercomprising 0.5-40 mass ppm one of B or Li.
 5. Au—Ag alloy bump accordingto claim 1, 3 or 4, wherein said bump comprises 5 to 25 mass % Ag. 6.Au—Ag alloy bump according to claim 1, 3, or 4, wherein said said rareearth element is at least one selected from the group of Y, La, Ce, Eu,Nd, Gd, and Sm.
 7. Au—Ag alloy bump according to claim 1, 3, or 4,wherein said Au—Ag bump is bonded to Pb-based solder or Sn-based solder.8. Au—Ag alloy bump according to claim 1, 3, or 4, wherein said Au—Agbump is bonded to Pb-free Sn-based solder in flip chip bonding.
 9. Au—Agalloy bump according to claim 1, 3, or 4, wherein in said flip chipbonding, said Pb-free Sn-based solder has a melting point in a range of170° C. to 260° C.